Lens system.



M. vor: 1201m LBNS SYSTEM. APPLIOATION FILED JUL! 15, 1909.

Patented Nov. 23, 1909.

OFFICE MOBI'IZ VON ROHR, OF JENA, GERMANY, ASSIGNOR T0 THEFIRM OF CARL ZEISS. OF

' JENA, GERMANY.

LEI\TS SYSTEM.

Specification of Letters Patent.

Patented Nov. 23, 1909.

Application filed J121y 15, 1909. Serial I\Io. 507,770.

citizen 0f the Gennan Empire and residing at Carl-Zeiss strasse, Jena, in the Grand Duchy of Saxe-Veimar, Germany, have inventecl a new and useful Lens System, of which the following is 21 specification.

Tl1e present invention relates to a 001- lective lens system f01 visual use consistin r 0f two lenses. not cen1ented, but place closely behind one another with a positive pair of facing surfaces, of Wl1ich lens0s the bindet one is collective and has a coneave hinder surface, further having a large field of View and being astigmatically correctecl :E0r a small diaphragm situated about 3 cm; behind the hinder lens. A lens system according to tl1is definition is one of. tl1e Zeiss Verantsystems, in Which 21 dispersive meniscus is employed as the front lens and a 001- lective meniscus as tl1e hinder lens. The V erant systems are designeol to proje'ct a distant image of a plane object (a photograph for instance) arranged in the f0cal plane of the system. At the locus of the small hinder diaphragm, which was supposed in the construetion, the eye as is well known is placed, so that its center of rotationwhich during '.ll movernent of the eye in direct Vision is the point of intersection 9f the principal rays eorresponding to the difl'erent positions 0f the center of the pupiloccupies as near as possible the positi0n of the Center of the diaphragm.

As perfectly as the Verant Systems are adapted to their proper task, namely to render p'ossible the correct viewing of photographs taken With an objective of the Same sl10rt .focallength, as is proper t0 tl1e system of observation, as little they a1e suitable for certain otl1er problems Which likewise l'equi1e a syste1n 0f the general prope'rties mentioned. F01 example, 110 one of the said Verant systen1s is applicable as a magnifying glass of medium power, because in the correspondin oblique penc1ls can no n1ore be sufl1ciently corrected. .Moreover, 110 one of the said systems can be e1nployed f01 the purpose 0f correcting a highly hypermetropic or aphacic eye, s'1nce in this case the weight of the glass W0111d be inadrnissi-bly large. Bu,tlaceording t0 the present invenon for tl1e said andsimilar purposes such 21 double lens colleetive system is qualified which bevery short foca'l length the longs to tl1e dass described at tl1e beginning und difl'ers principally frorn tl1e above n1en t1oned one 0f tl1e Verant systems (111 which .both lenses are meniscal, but only tl1e bindet one collective) in that the front lens is also collect1ve. If this new systen1 be employed for solvmg tl1e problen1s indicated, it is 'possible to eliminate astign1atism f01 a reat inclination 0:E tl1e p1incipal rays or at east 10 reduce it t0 21 hardly perceptible degree. At the Same time the distortion 0f the systen1 ca11 be removed t0 such an extent, tl1at, in the specially unfavorable case 0f a spectacle glass intended to enable an apl1acic eye for reading, it only' amounts to a fraction of the distort1on of a simple collective lens l1aving the san1e focal length.

It rnay here be mentioned, that tl1e Freneh oculist PEIYI1t had 211ready in the year 1897 (Socz'a'te' dOplzt/wlmologze, page 350) stated the general idea of giving two lenses 0f short distance t0 the aphacic eye, in Order (hat the spherico-cylindrical correction coulcl be distributed over four surfaces 111- stead 0f two, nmnely, over tl1ree spl1erical and one cylindrical surface. It Will be un derstood, that for tl1e correction of astig.

plied. The application 0f a given f01111 f0r anotl1er purpose tha11 tl1at for wl1ich lt is designed is in n1ost cases impossible in 0011- sequence of tl1e difference in tl1e degree 01. convergence 0f tl1e penclls e11tcring tl1e syste1 n, which covresponds t0 the difierence in the distance oli tl1e object. In s01110 cases such application.i further impossible 011 ae count of the difie1ence in tl1e deg1ree or' 0011- vergence required for tl1e e1nergingpencil (entering tl1e eye). F10111 tl1e s11111e re-asons one and tl1e san1e external f01'111 of tl1e ne\\ system 'd0 es not pern1it of an equally g1 10d eorrction for all purposes of uppl'1cation. Henne invesfigationwith referenc'e 10 the frin of the frontlens l1as 1esulted in provinE tl1e biconvex forn1 \\"11l1 regurd to tl1e correction of the system advantngcous when the new System is en1ployed us 21 11111g- .and t0uch 0ne another in the axis.

nifyinq glass 0f moderate power. On the other band a powerful collective system for corrective specfacles cmn be most perfectly corrected fox nstigmatism, When 1ts freut lens is also a meniscu und hus its concave surfaee also tu1ned toward the diaphragm.

111 i;he annexed dra\vingz Figure l is an axial section thfough a. 1ens system comstructed a.ccording to the invention. Fig. 2 is a similar section through gnother 1ens system. Fig. 3 is a similar section through a th ird lens system.

The lens system shown in Fig. 1 is a magnifying glass compased 0f two collective lenses Which have the refractive index 1.52 The front lens I is bieonvex, the hinder 0ne II a meniscus having its concave surface turned toward the diaphragm D. The radii 0f curvature, the thicknesses ab the vertex and the distance 0f the diaphragm are (for 14.4: mm. focal length, z. e. a magnification 250:44.4=5.6):

13::52.9 mm. 73 300 mm. .:43.7 mm. 73:800 mm. ch=4.0 mm. cZ= 1.0 mm. Z=29.0 mm.

The astigmatic correction can be seen from the following tab1e, in which according t0 the form of representation in use f0r hoto graphic 0bject1ves the distances. s and s.are given as measured in the difection of the axis between the vertex 0f the front surface 0f Baus I and the points of intersectioh of the t ..vo entering component pencils, the sagittml und tangential respectively, which correpond to a pencil emerging With paralle1 mys and with the incli qation w t0' the The duble 1ens spectzicle sys fem of Fig. 2 cgrrects an aph:icic"eye for distance. The front lens I and the bindet lens II have': b0th the refractive index 1.61. B0th a1e menisci, g

which have the concave su'rface turned towa.rd the' diaphragm D, and touch eac h: other in their vertices. The focal length 1s i 73:68.2 -mm. 73==29.2 mm.

d =3.0 mm. dn=2.0 mm.

13:38.6 mm. Z:"G.O mm.

Information as to astigmatic correction is g1ven m the follow1ng statement of the values s zind s being the true distances between the points of intersection 013 the emerging astigmzxtic pencils and the pluce where these pencils emerge from the hinder surfnce 0f lens II, as-well as the inclination w, which the corresponding entering pencil has to the axis.

w s f s,

0 86.08 mm. 86.08 mm. 17 .78 91.16 90.95 26.365 97.72 97.54.

73:45.01 min. 1g=95.64 mm. 7 .=30.5 mm. 13:46.3 'mrn. ch=8. mm. d :2.8 Inn1. Z=26.0 mm.

The degree 0f the astigmatic correction is given by the following values:

' w .s', s,

0 86.16 mm. 86.16mm. 14.859 90.34 89.38 21.832 95.63 93.49

l. A collective 1ens system for visual use over a 1a1ge field, consisting of twq simple collective lenses placed closely together wvith a positive pair 0f facing surfaces, the

- 1 hindel' 1ens lmving a concave hinder surface.

2. A collective lens system fo'r visuul use (wer a large field, consistiny of tw0 simple collective lenses placed closefy t0gether with a positive pairof facing surfaces, the hinder 1en s having a concave bindet SLI1fIICG und thesystern being astigmatically corrected f0r a narraw diaphragm lying about 3 cm. behind the vertex of the hindmost surface.

A collective lens system f0r visua1 use over a large field, consisting of two simple collective lenses placed closely together with a positive pair of facing surfaces, euch lens having a c3ndave hinder surface and. the

system being ustigmatically corrected f0r a nar1oW diaphragm 1ying about 3 cm. behind the vertex 0f the hindmost surface.

MORIIZ VON ROHR.

VVitnesses:

PAUL KRGER, FRITZ SANDER. 

